The plasma display panel (PDP as used hereinafter) has recently come to be the center of interest as it would provide a basis for development of a wall-mount television receiver set. The plasma display panel currently available in the market is of a structure shown in FIG. 8 and will now be discussed.
The prior art plasma display panel is shown in FIG. 8 in a partially cut-out perspective representation. In this prior art PDP, first and second substrates 1, 2 are disposed in face-to-face relationship with a plurality of elongated partition walls 3 intervening therebetween, and a rare gas is filled between the first and second substrates 1, 2. A plurality of elongated scanning electrodes 4 are arranged parallel to each other on a surface of the first substrate 1. Also, a plurality of elongated sustaining electrodes 5 are arranged parallel to each other in an alternating fashion with the scanning electrodes 4 on the surface of the first substrate 1. A dielectric layer 6 is formed on the surface of the first substrate 1 so as to cover the scanning and sustaining electrodes 4, 5, which is in turn covered by a protective layer 7. A plurality of data electrodes 8 are provided on a surface confronting the first substrate 1, which are elongated in a direction perpendicular to the scanning and sustaining electrodes 4, 5. A discharge cell 9 is formed at intersection of the scanning and sustaining electrodes 4, 5 and the data electrode 8. The data electrodes 8 are set apart form each other by the partition walls 3, respectively. A fluorescent material 10 is deposited between the partition walls 3 so as to cover the data electrode 8. A unitary pixel is defined by one scanning electrode 4, one sustaining electrode 5 and one data electrode 8. A unitary pixel is defined by one scanning electrode 4, one sustaining electrode 5 and one data electrode 8.
A gradation display method of this prior art PDP such as described in the Japanese Laid-open Patent Publication No. 4-195188, published in 1992, is shown in FIG. 9. In this prior art PDP, a single field representative of one picture is divided into eight sub-fields b.sub.0 to b.sub.7 and each sub-field is also divided into an address interval and a sustaining interval. During the address interval, scanning electrodes 4 are sequentially selected to allow data to be written in all pixels. During the sustaining interval following the address interval, an alternating voltage is applied between the scanning electrodes 4 and sustaining electrodes 5 to cause all of the pixels, in which the data was written, to energized to emit light for a predetermined duration. By choosing the proportion of the length of the sustaining interval of each sub-field to be 1, 2, 4, 8, 16, 32, 64 and 128, a display in 256 gradation levels, that is, a 256 gradation image can be obtained.
With the prior art PDP, increase of the number of the electrodes in an attempt to increase the definition of displayed images tends to result in reduction of the address interval allocated to each scanning electrode and, therefore, this involves a problem associated with the discharge not occurring assuredly. By way of example, if the 256-level gray scale image is to be displayed by a high-definition PDP having 1,000 or more scanning electrodes, the length of time allocated for data write-in would be (1/60).div.1,000.div.8.apprxeq.2 .mu.s or smaller for each scanning electrode. While the length of time required for a discharge to be formed in each discharge cell of the PDP is generally equal to or lower than 1 .mu.s, the length of time required to complete the discharge formation often fluctuates and, therefore, the discharge formation often takes about a few microseconds. In view of this, when the width of the write-in pulse is equal to or smaller than 2 .mu.s, there is a considerably high risk of occurrence of a write-in error in which a write-in discharge will not set up sufficiently, which eventually brings about drop-out and/or flickering taking place in the displayed image.
Also, in the high-definition PDP, in order to increase the aperture and/or to avoid any possible contact or interference between the neighboring electrodes, efforts have centered on reducing the width of each electrode to a value as small as possible. In such case, there is a considerably high risk of occurrence of rejected products as a result of breakage of the electrode during the manufacture of the PDPs.
Even though no breakage of the electrodes occur during the manufacture of the PDPs, the electrodes if partially small in width are susceptible to breakage during the use thereof as a result of heat generated upon supply of an electric power therethrough. Once this occurs, the electrodes will no longer be useable. Inspection as to the presence or absence of the partially small width in the electrodes has been extremely difficult to achieve.